Certain optical systems, such as projection systems and automobile headlights, require light sources with high radiance or luminance. Until recently, the luminance of conventional light emitting diodes (LEDs) was inadequate to fulfill the needs for such applications. However, even with current high performance LEDs, the radiance requirement for some optical systems is difficult to fulfill. Moreover, in comparison to high intensity discharge lamps, the luminance of LEDs is typically too low. This is particularly true in systems that convert light emitted from LEDs, e.g., using phosphor, to other wavelengths in order to produce white light. Such conversion typically results in a loss of radiance rendering such systems unacceptable for high brightness applications.
Thus, what is needed is an improved high radiance optical system.